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Org. Synth. 1953, 33, 23
DOI: 10.15227/orgsyn.033.0023
DIETHYL 1,1-CYCLOBUTANEDICARBOXYLATE
[1,1-Cyclobutanedicarboxylic acid, diethyl ester]
Submitted by Raymond P. Mariella and Richard Raube1.
Checked by William S. Johnson, William DeAcetis, and Herbert Title.
1. Procedure
A solution of sodium ethoxide is prepared by adding 138 g. (6.0 g. atoms) of fresh-cut sodium in small pieces to 2.5 l. of absolute ethanol in a 5-l. round-bottomed flask fitted with an efficient reflux condenser capped with a calcium chloride drying tube (Note 1). In a three-necked 5-l. round-bottomed flask, equipped with a reflux condenser capped with a calcium chloride tube, a rubber-sealed mechanical stirrer, and an inlet tube for addition of the sodium ethoxide solution, are mixed 480 g. (3.0 moles) of diethyl malonate (Note 2) and 472 g. (3.0 moles) of trimethylene chlorobromide (Note 3). The mixture is heated to 80° and vigorously stirred while the sodium ethoxide solution is slowly forced into the flask by means of dry air pressure. The rate of addition is regulated so that the reaction mixture refluxes smoothly. After the addition is complete (this requires about 1.5 hours), the mixture is refluxed, with continued stirring (Note 4), for an additional 45 minutes. Upon completion of the reflux period, the alcohol is removed by distillation (Note 4), 90–95% of the alcohol being recovered. The reaction mixture is cooled, and 900 ml. of cold water is added. After the sodium halides are completely dissolved, the organic layer is separated and the aqueous layer is extracted with three 500-ml. portions of ether. The organic layer and the ether extracts are combined, shaken with 50 ml. of saturated salt solution, and dried over 100 g. of anhydrous sodium sulfate. The solution is filtered, the ether is removed by distillation on a steam bath, and the residue, which weighs 600–625 g., is distilled through a short Vigreux column. The yield of product boiling at 91–96°/4 mm. is 320–330 g. (53–55%) (Note 5).
2. Notes
1. It is important to maintain strictly anhydrous conditions throughout this reaction. The equipment should be carefully predried and the absolute ethanol freshly prepared (preferably by the magnesium ethoxide method2) and distilled directly into the reaction flask. If the volume of ethanol is less than 2.5 l. the sodium ethoxide may not remain in solution. It is convenient to employ a three-necked flask carrying two condensers for this operation and to add the sodium through the third neck, which is otherwise kept stoppered.
2. Material boiling at 95.2–95.8°/14 mm., n25D 1.4120, was used.
3. Trimethylene chlorobromide can be obtained commercially. Material boiling at 141–142°/755 mm., n25D 1.4843, was used.
4. The stirring must be continued during this operation; otherwise the mixture will bump badly.
5. This material, n25D 1.433–1.434, d2520 1.042–1.044, is of fair purity and can be hydrolyzed and decarboxylated3,4 to give cyclobutanecarboxylic acid in more than 80% yield. In order to obtain a highly pure product it may be necessary to fractionally distil the material. For example, on slow redistillation of a product prepared as described above through a 3-ft. Vigreux column at a high reflux ratio, the checkers obtained 8.5% of forerun n25D 1.4287–1.4328, 43% of diethyl 1,1-cyclobutanedicarboxylate, n25D 1.4332–1.4335, and 2.5% of higher-boiling material n25D 1.4362–1.4427. The pure product is reported to boil at 104.6°/12 mm., 85.2°/3.5 mm. or 60.0°/0.5 mm., n25D 1.4336, d2520 1.0470.5
3. Discussion
Diethyl 1,1-cyclobutanedicarboxylate has been prepared by the alkylation of diethyl sodiomalonate with trimethylene dibromide,3,4,6,7 trimethylene diiodide,7 or trimethylene chlorobromide.8,9 It is claimed that the yield of product from the latter reaction may be increased by the use of a mixture of benzene and ethanol as a solvent.10 Diethyl 1,1-cyclobutanedicarboxylate also may be obtained by the peroxide-catalyzed addition of hydrogen bromide to diethyl allylmalonate followed by intramolecular alkylation.11 The procedure described here is that of Mariella and Raube.8
This preparation is referenced from:

References and Notes
  1. Northwestern University, Evanston, Illinois.
  2. Lund and Bjerrum, Ber., 64, 210 (1931). Fieser, Experiments in Organic Chemistry, 3rd ed., p. 286, D. C. Heath and Company, Boston, Massachusetts, 1955.
  3. Org. Syntheses Coll. Vol. 3, 213 (1955).
  4. Cason and Allen, J. Org. Chem., 14, 1036 (1949).
  5. Perkin, J. Chem. Soc., 51, 1 (1887).
  6. Rupe, Ann., 327, 183 (1903).
  7. Gol'mov, Zhur. Obshcheii Khim., 22, 1944 (1952) [C. A., 47, 9268 (1953)].
  8. Mariella and Raube, Bol. col. quím. Puerto Rico, 8, 24 (1951) [C. A., 46, 4491h (1952)].
  9. Kishner, J. Russ. Phys. Chem. Soc., 37, 507 (1905) [Chem. Zentr., [2] 76, 761 (1905)]; Favorskaya and Yakovlev, Zhur. Obshcheii Khim. (J. Gen. Chem.), 22, 122 (1952) [C. A., 46, 11118 (1952)]; Gol'mov and Kazanskii, Akad. Nauk. S.S.S.R. Inst. Org. Khim. Sintezy Org. Soedinenii Sbornik, I, 93 (1950) [C.A., 47, 8003 (1953)].
  10. Raik and Kazanskii, Vestnik Moskov. Univ., 8, No. 3, Ser. Fiz.-Mat. i Estestven. Nauk, No. 2, 125 (1953) [C. A., 49, 3833 (1955)].
  11. Walborsky, J. Am. Chem. Soc., 71, 2941 (1949).

Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

ethanol (64-17-5)

Benzene (71-43-2)

ether (60-29-7)

hydrogen bromide (10035-10-6)

trimethylene dibromide (109-64-8)

sodium sulfate (7757-82-6)

sodium (13966-32-0)

sodium ethoxide (141-52-6)

Trimethylene chlorobromide (109-70-6)

diethyl malonate (105-53-3)

Diethyl 1,1-cyclobutanedicarboxylate,
1,1-Cyclobutanedicarboxylic acid, diethyl ester (3779-29-1)

diethyl sodiomalonate

trimethylene diiodide (627-31-6)

diethyl allylmalonate (2049-80-1)

Cyclobutanecarboxylic acid (3721-95-7)